Chemical Approach to a New Crystal Structure: Phase Control of Manganese Oxide on a Carbon Sphere Template

The stabilization and growth of a non‐native structure, hexagonal wurtzite MnO (h‐MnO), is explored via kinetic control of manganese precursor on a carbon sphere template. MnO is most stable in the cubic rock‐salt structure (c‐MnO), and a number of studies have focused on the synthesis and properties of this rock‐salt phase. However, h‐MnO has not been fully characterized before our work. Prolonged heating at a relatively low temperature yields c‐MnO, whereas rapid heating of the reaction mixture at reflux produces h‐MnO in the presence of carbon spheres. The effect of benzyl amine concentration on the formation of two different oxidation states (c‐MnO and t‐Mn₃O₄) was examined as well. Moreover, the structural stability of the manganese oxides and phase transition of MnO in terms of the wurtzite to rock‐salt structural transformation have been investigated.